13
INSTALLATION AND OPERATION MANUAL
thermometer. When the targeted water temperature (75° C) is reached, fix the damper 4 to the lowest position by fastening the
lever of the draught regulator and choosing the length of the connecting chain. Remember: a 9 mm gap should be left between
the damper and the air supply opening. The exact size of the gap depends upon the draught of your chimney. The worse the
draught, the greater the gap should be.
• ReGUlaTIon of THe seconDaRY aIR DaMPeR
The secondary air damper 6 (Fig. 8) is set up in the factory. To inspect the positioning of the damper: loosen the fixing screw
and push the shaft of the damper forward until it gets stuck. Then pull the shaft 5 mm backwards and fix it with the screw.
• conTRollInG THe TeMPeRaTURe of WaTeR ReTURnInG To THe boIleR
It is absolutely necessary to maintain the
temperature of the water returning from the
heating system to the boiler at a constant
level, no less than 65°C, as this will prolong
the lifetime of the boiler and will make the
combustion process more effective. This is
because when a constant high temperature
of water returning to the boiler is maintained,
there arises significantly less water vapour
condensation inside the boiler. The heavy water
condensation is harmful to the boiler, because
deposits of tar, pitch and soot accumulate on the walls of the heat exchanger, causing intense metal corrosion. Moreover, the
resulting layer of soot impedes effective heat transfer and the efficiency of the boiler falls.
In order to maintain the temperature, we recommend installing the small circulation circle together with a Swedish-made
thermoregulation device, “Laddomat 21-100”. Make sure that the “Laddomat” is supplied with the 72°C thermostat cartridge.
The mentioned temperature is the one at which the valve of the device opens completely. However, the actual temperature
of the water returning from the system and getting into the boiler after mixing, is 5-6°C lower. The higher the temperature
of the return water is, the better it is for the boiler. Thermoregulation devices of other manufacturers could be used for
maintaining the temperature of the returning water as well.
• HeaTInG oUTPUT, WaTeR TeMPeRaTURe anD WaTeR floW RelaTIonsHIP
The heating output supplied to a heating system depends directly upon the difference of flow and return water temperatures
Δt and the intensity of the water flow circulating through the boiler. The boiler will fail to reach the desired temperature of the
flow water if the returning water temperature is too cold or the circulation pump is too powerful. This will happen because
the boiler will be forced to produce a larger heating output than it has been designed for. The most effective boiler operation
occurs when the difference between the flow and return water temperatures is 13-18°C. If the boiler is forced to operate
with a 20°C or even greater temperature difference, it will work ineffectively, consume too much of fuel, and the combustion
period of one fuel load will consequently shorten. If the previously mentioned difference of temperatures is kept less than
10°C, the fuel in the boiler will again burn inefficiently and fume because of a lack of air supply. If you know the water flow
intensity near your boiler, in the above presented table you can check, what the difference of flow and return temperatures
your boiler is capable to maintain, when operating at the nominal heating output.
Do not forget to keep the returning water temperature as high as possible, at least 65°c or even higher!
It is necessary to assure that a thermometer is installed on the returning water pipe, in order to be able to
observe this temperature at any time!
Difference of water temperatures
Δt, °c
Heating output, kW
50
Water flow, l/min
11
67
12
61
13
56
14
52
15
49
16
46
17
43
18
41
